So one example would be a firm that they both earn, sorry, they both own, and another example would be two of you working as a study group on my homework assignment.

也就是说这两家公司互相赚钱,我说错了,是交叉控股,另外一个例子是两名同学,为了做作业组成了一个学习小组

耶鲁公开课 - 博弈论课程节选

If you have profit sharing in a firm or profit sharing in homework assignment, or any joint projects, you have to worry about too little effort being contributed because there's an externality.

如果你是一个公司的股东,或者和别人一起做作业及其他合作项目,你们需要注意到因为外部性,实际上每个人都付出了较少的努力

耶鲁公开课 - 博弈论课程节选